linux-kernel - Re: [PATCH 4/5] clk: sunxi-ng: a64: Add constraints on PLL-VIDEO0's n/m ratio

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Date: Fri, 22 Dec 2023 08:46:01 +0100
From: Frank Oltmanns <frank@...manns.dev>
To: Jernej Škrabec <jernej.skrabec@...il.com>
Cc: Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Chen-Yu Tsai <wens@...e.org>, Samuel Holland
 <samuel@...lland.org>, Guido Günther <agx@...xcpu.org>,
 Purism Kernel Team
 <kernel@...i.sm>, Ondrej Jirman <megi@....cz>, Neil Armstrong
 <neil.armstrong@...aro.org>, Jessica Zhang <quic_jesszhan@...cinc.com>,
 Sam Ravnborg <sam@...nborg.org>, Maarten Lankhorst
 <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
 Daniel Vetter <daniel@...ll.ch>, linux-clk@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
 linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 4/5] clk: sunxi-ng: a64: Add constraints on PLL-VIDEO0's
 n/m ratio


On 2023-12-20 at 16:12:42 +0100, Jernej Škrabec <jernej.skrabec@...il.com> wrote:
> Dne sreda, 20. december 2023 ob 08:09:28 CET je Frank Oltmanns napisal(a):
>>
>> On 2023-12-19 at 17:54:19 +0100, Jernej Škrabec <jernej.skrabec@...il.com> wrote:
>> > Dne ponedeljek, 18. december 2023 ob 14:35:22 CET je Frank Oltmanns napisal(a):
>> >> The Allwinner A64 manual lists the following constraint for the
>> >> PLL-VIDEO0 clock: 8 <= N/M <= 25
>> >>
>> >> Use this constraint.
>> >>
>> >> Signed-off-by: Frank Oltmanns <frank@...manns.dev>
>> >> ---
>> >>  drivers/clk/sunxi-ng/ccu-sun50i-a64.c | 8 ++++++--
>> >>  1 file changed, 6 insertions(+), 2 deletions(-)
>> >>
>> >> diff --git a/drivers/clk/sunxi-ng/ccu-sun50i-a64.c b/drivers/clk/sunxi-ng/ccu-sun50i-a64.c
>> >> index c034ac027d1c..75d839da446c 100644
>> >> --- a/drivers/clk/sunxi-ng/ccu-sun50i-a64.c
>> >> +++ b/drivers/clk/sunxi-ng/ccu-sun50i-a64.c
>> >> @@ -68,7 +68,8 @@ static SUNXI_CCU_NM_WITH_SDM_GATE_LOCK(pll_audio_base_clk, "pll-audio-base",
>> >>  				       BIT(28),	/* lock */
>> >>  				       CLK_SET_RATE_UNGATE);
>> >>
>> >> -static SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_CLOSEST(pll_video0_clk, "pll-video0",
>> >> +static SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_FEAT_NM_RATIO(pll_video0_clk,
>> >> +						"pll-video0",
>> >>  						"osc24M", 0x010,
>> >>  						192000000,	/* Minimum rate */
>> >>  						1008000000,	/* Maximum rate */
>> >> @@ -80,7 +81,10 @@ static SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_CLOSEST(pll_video0_clk, "pll-vid
>> >>  						297000000,	/* frac rate 1 */
>> >>  						BIT(31),	/* gate */
>> >>  						BIT(28),	/* lock */
>> >> -						CLK_SET_RATE_UNGATE);
>> >> +						CLK_SET_RATE_UNGATE,
>> >> +						CCU_FEATURE_FRACTIONAL |
>> >> +						CCU_FEATURE_CLOSEST_RATE,
>> >
>> > Above flags are unrelated change, put them in new patch if needed.
>>
>> You might notice that I am using a new macro for initializing the
>> pll_video0_clk struct:
>> New: SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_FEAT_NM_RATIO
>> Old: SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_CLOSEST
>>
>> Setting the two CCU_FEATURE flags is part of the old initialization
>> macro.
>>
>> I'll add SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_NM_RATIO_CLOSEST which
>> hopefully resolves the confusion.
>
> I'm in doubt if we need so many macros. How many users of these macro we'll have?
> I see that R40 SoC would also need same ratio limits, but other that that, none?

Ok, IIUC no additional macro and we keep this part of the patch as is.

Best regards,
  Frank

>
> Best regards,
> Jernej
>
>>
>> Thanks,
>>   Frank
>>
>> >
>> > Best regards,
>> > Jernej
>> >
>> >> +						8, 25);		/* min/max nm ratio */
>> >>
>> >>  static SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK(pll_ve_clk, "pll-ve",
>> >>  					"osc24M", 0x018,
>> >>
>> >>
>>